Bit holder



Feb. 4, 1947. MQRRQW v m 2,415,107

BIT HOLDER Filed Feb. 28, 1944 II II Patented Feb. 4, 1947 ossice BIT HOLDER Harry M. Morrow, Canton, Ohio, assignol to The Bowdil Company Application February 28, 1944, Serial No. 524,185

My invention relates to mining machine cutting chains and more particularly to a bit holding body.

The-mining machine chain in which this bit holding body is employed-is the type consisting of an endless chain. Each of the several bits heldin the chain lugs of the endless chain will cut its equal share only if all are maintained at a uniform distance Or gauge from the chain lug.

' An object of my invention is the provision for holding a cutting bit at a uniform distance or gauge from the chain lug.

Another object of my invention is the provision for holding a bit within the recess of a chain lug with a clearance between the cutting face of the bit and the recess so as not tointerfere with the proper gauging of the bit in the chain lug.

Another object of my invention is the provision'of a Wedge-grip holder or a self-locking grip holder for a mining machine cuttingbit.

Another object of my invention is theprovision of non-wedging surface areas to prevent a cutting bit from locking or wedging too tight into its holder.

Another object of my invention is the provision for aligning a cutting bit in the chain lug. for either forward or reverse cutting.

Other objects and a fuller understanding of my invention may be had by referring to the following description and claims, taken in conjunction with the accompanying drawing, in which:

Fig. 1 is a side elevational view of a mining machine chain lug havinga bit holder embodying my invention;

Fig. 2 is a longitudinal cross-sectional view of the mining machine chain lug and bit holder shown in Fig. 1;

Fig. 3 is a fragmentary and enlarged view shown in cross-section, taken along the line 33' of Fig.2;

Fig. 4 is a plan view of the mining machine chain lug with the bit holder, and set screws removed;

Fig. 5 is a view taken normal to one of the cutting faces of a type of cutting bit Which may be used in my bit holder;

Fig. 6 shows a side elevational view of a combination of my bit holder and a type of bit-that may be used therein.

Fig. 7 is a front elevational view of my bit holder; and a Fig. 8 is a cross-sectionalviewtaken alongthe line 88of Fig. 6.

8 Claims. (01. 262-33) With reference to the drawing, a mining' machine chain lug unitto carry a bit holder embody+ ing the features of my invention may comprise a chain lug I0 having achain body III, a bit holder I2 for receiving a bit 13, and set screws M and Ii -for holding the bit holder l2 and its contained bit I3 within a recess 16 of the chain body I I.

The cutting bit may be of any suitable type and'ispreferably of the double-ended or pointed type having a rliomboidal outline in side elevation and having substantially diamond shaped parallel end cutting faces offset relative to each other at a rhomboidal angle. In other words, the'bitmay be of the type illustrated'in Patent No. 1,677,950, issuedJuly 24; 1928, to N. KQBoW- man, orof the type illustrated] in PatentiNo'. 2,217,347, issued October 8, 1940, to the present applicant, on of'the type illustrated inPatentNO; 2,217,348, issued October 8; 1940, to CharlesL. Bowman, the latter'two types of bit havingconcaved or'depressed side portions to provide acutting clearance as the points of the bits wear away. i

The recess-"16in the" chain body I I. comprises an" oval opening with substantially straight side wailportions and'subst'antially oval endwall portion's; As shown in Figures 2 and 3, the recess I6 is provided'with a slot llon the left-hand oval end wall thereof and a slot I8 0n the righthand oval end wall thereof to receive a sloping key-projection l9 of'the bit holder. l2. The key projection 15 into theslot I! on the lefthand' oval end wall' of recess l6 whenever the direction of motion of the chain lug H is to the right, and it fits into the slot I8 of the righthand oval end wall of recess 16 whenever thedirection of motion of the chain log! 5 is in the re* verse direction to the left to assure proper alignment of the bit holder. The dimensions of the key projection are such that, with respect to slot l1 and slot I8, substantially'no binding or pres-'- sure will beexerted between their respective walls,

infact a clearance 23 is provided to insuresuch a condition. The: slots I? and I-Bare also respectively disposed to receive the inactive portion of the cutting face of the bit. It, the particular slot. receiving the cutting face depending upon the direction ofthe cutting movement of the chain. Thus for one-direction of cutting the slot ll receives the inactive portion of the cutting face 25 of the bit 13 as the assembled combination of .bit holder' I2 and bit l3 are inserted into the chaining recess'lli with key projection 19 fitting into slot [8; andfor the reverse direction of cutting the slot- [8 receives the inactive portion of cutting face 25 as the assembled combination is inserted into the chain lug recess with key projection l9 fitting into slot H.

v the pair of surfaces 29 and 26 on the bit with an overhanging shoulder which engages respectively the top 2| or 22 of chain lug body It to provide stop means to limit the insertion of r the holder in the recess IE to a definite place for establishing a predetermined gauge for the bit. Upon the arresting of the inward movement of the holder in the lug recess by the stop shoulder 20 engaging the top of the lug, a clearance 24 will exist between the forward inactive portion 38 of the cutting face 25 of the bit l3 and the bottom surfaces of either slot [1 or slot l8 of recess 16, depending upon which of the slots is receiving the forward face of the bit, whereby the gauge is not affected by a wedging of the inactive portion 38 of the cutting face of the bit against the bottom of the respective slots I! or IR as the holder is moved inwardly in the lug recess.

5 The bit holder it has a bit'receiving socket formed by a bit backing wall 33 and side walls 39 and 3| which reach an apex at a sloping V at 32. The rear or inactive cutting face 26 of a.bit i3.engages thebit backing wall 33' of the bitxholder l2, and the sloping edge 2? of the bit 13 engages the apex 32 of the bit holder !2. The apex 32 and the bit backing wall 33 of the holder form' an included angle of substantially or less into which the bit is wedged to secure same into the holder. In practice it has beenfound that'inthe bit socket with converging surfaces of substantially 30 or less a wedging action'is produced to grip an inserted bit therein with a sufficient force to keep the bit from coming out. Hence the term wedge-grip is applied to surfaces forming an angle which when the bit is inserted therebetween, produces a self-locking.

grip. Any angle greater than 30 tends towards weakening of. the grip until a point is reached .Where no grip occurs even though the bit be driven in hard between the angularly disposed surfaces.

The sides 28 and 29 of the bit I3 engage the side walls 30 and 3| of the bit receiving socket, and the inserted cutting point of bit i3 extends freely into a hole 34 in the shank or lower position of said bit holder 52. When the cutting bit l3 is inserted into the bit receiving portion of bit holder l2 it may be given a tap with a tool on its protruding point to wedge the bit into the bit holding portion. The surfaces 26 and 21 of the bit, and surfaces 32 and 33 of the bit receiving socket. produce a wedge-grip action on the bit to hold it securely therein. Other complementary their complementary surfaces 3| and 33 of the bit receiving socket of bit holder I 2, at their areas furthest removed from the apex 32, form angles larger than a wedge-grip angle to oppose the wedging of the bit into the socket so thatthe' 7 bit will not lodge too tight. The hole 34 is provided in the shank portion of the bit holder 12 to prevent foreign material from collecting in'th'e bit receiving socket which would otherwise interfere with the insertion of the bit.

*The chain lug body II has angularly disposed :set'scre'w threaded openings registering with the lug recess 6 at the bottom portion thereof and receiving the set screws [4 and [5 which secure the bit holder and bit in the lug recess it by engaging downwardly diverging surfaces 35 and 36 of the shank portion of bit holder l2. With this invention the bit may be removed from the bit receiving socket by disengaging set screws !4 and i5 from'the diverging shank surfaces 35 and 36 of the bit holder l2 and grasping the bit holder by the finger grip portions 3? which may be provided to facilitate the removal of the bit holder from the chain lug recess 56. The assembled bit holder 22 and its contained bit is then raised a short distance outwardly with respect to the chain lug recess 16 in order that the path of extraction of said cutting bit :3 will not be blocked by the bot: tom wall of sloping notches I? and I8 of recess iii depending upon which one of said notches inactive portion 38 of cutting face 25 is extending into. and I8 of recess H5 or provided at such an angle that they will interfere with the removal of cutting bit l3 unless the said combination of bit holder and bit are first partly withdrawn from the bit with their complementary surfaces 30 and33 of the bit receiving socket of bityholder l2 and recess Hi. This construction is for the purpose of preventing any bits that should possibly come loose from the bit receiving socket from becoming lost, and maintains the bits in the socket until the next impact which wedges the bit firmly in the socket. With the bit then partially withdrawn from the chain lug recess [6, the contained bit l3 may be loosened from its holding socket by taping its exposed surface 21 with a tool at an angle substantially normal to the surface, after which thebit can beeasily removed.

Although I have described myinvention with a certain degree of particularity, it is understood that the present disclosure has been made only by way of example and that numerous changes in the details of construction and the combination and arrangement of parts may be resorted to without departing from thespirit and scope of the invention as hereinafter claimed.

I claim as my invention:

1. In a chain lug body having a top surface and having a recess with an end wall portion, the combination with a bit of rhomboidal side elevae tion, and having substantially diamond shaped cutting faces producing cutting points, of a bit holder, said bit holder comprising a body having a bit receiving portion, a bit backing wall portion and a shank portion to fit in said recess, the inactive cutting face of said bit engaging said bit back- 4 ing'wall portion of the bit holding body, said bit holder body having stop means to contact the top surface of said chain lug to limit the inward movement of said holder in said recess and thereby maintain a cutting point of said bit atsubstantially a constant distance from top surface'of said chain lug, said bit receiving portion having at least two angularly disposed inner wall surface portion forming wedge-grip angle with, and

The bottom walls of sloping notches l1 3 being complementary to the engagedjsur'face area'sfof said rhomboidal bit, said angularlydis posedj' inner wall surfaces maintaining said bit in a cuttingflpositioi'i' in'said holder with the other of said cutting facesfoffsaid bit extendingfor wardly and 'outwardlywith every portion'of said face clearing the said end'wall portion of said lugljrecess. 1

2. In a chainlug body' having a topsurface and-having a recess with an end wall portion, said chain lug having a threaded opening regis tering with the recess and having a set screw' therein, the combination witha bit of rhomboidal side elevation and having substantially diamond body, said shank portion having a downwardly diverging surface portion'against Whichthe set screw engages for holding ,the bit holder and bit therein firmly within said recess, said bit holder body having stop means to contact the top surface of said chain lug to limit the invvardmovement of said holder in said recess and thereby maintain a cutting point of said bit at substantially a constant distance from top surface of said chain lug, said bit receiving portion having at least two angularly disposed inner wall surface portions forming a wedge-grip angle with, and being complementary to the engaged surface areas of said rhomboidal bit, said angularly disposed inner wall surfaces maintaining said bit in a cutting position in said holder-with the other of said cuttingjfa'cesof said'bit-extending forwardly and outwardly with every portion of said face clearing the said end wall of said lug recess;

3. ma chain lugblock havinga recess; the improvement of'a bit holder receivable in said recess, a bit to fit'into' said holder, said holder having a bit receiving portion with fixed inner wall surfaces defining a bit're'ceiving recess to receive said bit, said bit having a forwardly and outwardly projecting cutting face, said bit receiving recess of said holder maintaining said bit in a cutting positionwith a portion of the cutting face disposed within the recess and a portion thereof extending therefrom and constituting an active cutting face of said bit, stop means to arrest inward movement of said holder into said recess to maintain a fixed cutting gauge for said bit, said stop means maintaining said bit cutting face within the recess at a distance away from the wall of said recess, whereby a space is left therebetween to prevent wedging before the stop means is in its stop arresting position.

4. In a chain lug having a recess with an end wall portion, the improvement of a bit holder receivable in said recess to hold a bit having at least one cutting face, said bit holder comprising a body having a bit receiving portion and a shank portion, said bit receiving portion having a bit receiving recess therein defined by fixed recess walls, said bit being disposed to fit into said bit receiving recess of the bit receiving portion with the said cutting face thereof projecting forwardly and outwardly therefrom, said bit receiving portion having stop means engaging the chain lug to arrest inward movement of said bit holder into said lug recess to maintain a fixed cutting gage for said bit, said holder maintaining said bit in a cutting position with a portion of the cutting face disposed within the recess and constituting an inactive cutting portion of-saidbit aiid a por-=* tion" thereof extending therefrom and' con'stitun ingaii-active cutting portion of said b'iti said stepmeans maintaining-said holderih position-t6 hold said cutting face int-spaced relationship to said recess, whereby wedg'ing between the said cutting face and the wall portionof the" recessispre vented.

face portions forminga wedge-grip self-locking angleto "lock said bit therein, said bit 'being dis posed to fit into said-bit receiving portionof tlie holder with the said cutting face thereof pr'o jecting forwardly and outwardly therefrom; said bit receiving portionhaving stop means engaging the chain lugto arrestinward movement of said bit holder into said lug recess'to maintain a fixed cutting gage for said bit, said holder maintaining said bit in a cutting position with a'portioh of "thecutting face disposed withinthe' recess andcon#=- stituting an inactive'cutting portion of said bit and a portion thereof extending therefrom"and constituting an active cutting portionof saidbitj saidstop means maintaining said holder'imposis tion to hold said cutting fa'ce'in spaced relation:

ship to said recess, whereby wedging between "th'e said cutting face andthe'wall portion'of the-re cess" is prevented. I

6. In a mining machine" chain" lug having "a" recess adapted to receive" a bit holder and having" an angularly disposedsetscrew threaded o en: ing registering" with the recess with a setscrew therein to engage a holder, the improvement "of a bit holder to fit into said recess and hold a double-ended rhomboidal bit having end cutting faces, said holder comprising a body havingan upper bit receiving socket portion" and having a lower anchoring portion, said bitreceiving socket portion having an inner back wall against which" an end cutting face of the biten'gages and: having inner lateral side walls embracing but a part of the sides of the bit with the remaining portion of the bit exposed, said walls of the bit, receiving socket forming wedge-grip angle with, and being complementary to, the engaged surface areas of said rhomboidal bit, said anchoring portion of the bit holder having a surface against which the said set screw may engage for drawing the bit holder firmly Within the recess, stop means on the bit holder body to contact the chain lug to limit the inward movement of the holder into said recess, and thereby maintain a cutting point of said bit at substantially a constant distance from the said lug, said wedge-grip inner wall surfaces of the holder maintaining said bit in a cutting position in said holder with the other of said cutting faces of said bit extending forwardly and outwardly with every portion of said bit face being in spaced relationship to said lug recess, whereby a space is left therebetween to prevent wedging between the cutting face of the bit and the wall portion of the recess.

'7. A mining machine chain lug adapted to hold a double-ended rhomboidal bit having end cutting faces, comprising in combination, a bit holder, a chain lug body having a recess to receive the bit holder, said recess having end wall portions and side wall portions, said end and side wall portions being substantially straight and defining an oval opening with the distance between the end wall portions constituting the major axis,

- said chain-lug body having at each end thereof an. angularly disposed set screw threaded opening registering with each of the said end wall portions of the recess, said bit holder having an upper bit receiving socket portion and having a lower anchoring portion, said bit receiving socket portion having a, back wall against which an end cutting face of the bit engages and having relatively shallow lateral walls embracing but a part of the sides of the bit with the remaining portion of the bit exposed, the said walls of the bit receiving socket forming awedge-grip angle with, and being complementary to, the engaged surface portion of said rhomboidal bit to wedgingly grip and hold the bit in the bit receiving socket, said bit receiving socket portion of said bit holder having substantially straight external side walls and straight external end walls to fit complementarily with the side wall portions and an end wall portion of the said recess, said anchoring portion of the bit holder having surfaces against which a set screw may engage for drawing the bit holder and a bit therein firmly Within the said recess, stop means on the bit holder to contact the chain lug to limit the inward drawing of the bit holder into the recess, and thereby maintain a cutting point of the said bit at substantially a constant distance from the said lug, each said end Wall of said recess having an inclined slot near the upper edge thereof, said holder wedgingly gripping and maintaining said bit in 'a cutting position in said recess with the other of said cutting faces of said bit extending forwardly andoutwardly from the chain lug body with every portion of said other cutting face being in spaced relationship to said inclined slot, whereby a space is left therebetween to prevent wedging betweenthe cutting face of the bit and the slot wall.

8."A' mining machine chain lug adapted to hold a double-ended rhomboidal bit having substantially diamond shaped end cutting faces and substantially concaved side faces comprising, in combination, a bit holder, a chain lug body having a recess to receive the bit holder, said chain lug body having an angularly disposed set screw threaded opening registering with the recess, said bit holder having an upper bit receiving socket portion and having a lower anchoring portion, said bit receiving socket portion having a back Wall against which an end cutting face of the bit engages and having lateral convexed side walls complementarily embracing but a part of the concaved side faces of the bit with the remaining portion of the bit exposed, the said walls of the bit receiving socket forming a wedge-grip angle with, and being complementary to, the engaged surface portion of said rhomboidal bit to wedgingly grip and hold the bit in the bit receiving socket, said anchoring portion of the bit holder having at least an end Wall portion against which a set screw may engage for drawing the bit holder and the bit therein firmly within the said recess, stop means on the bit holder body to contact the chain lug to limit the inward movement of the holder into the said recess and thereby maintain a substantially constantgag'e for the said bit, the said holder maintaining said bit in a cutting position in said recess with the exposed cutting face of the said bit extending forwardly and outwardly from the chain lug body with every portion of said face in spaced relation with the walls of the said recess, whereby wedging between the said exposed cutting face and the wall of the recess is prevented.

HARRY M. MORROW.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS McCullough Sept. 2, 1941 

